willingness vs openness

willingness and openness both are nouns.

Word	Noun	Adjective	Verb	Adverb
willingness	Yes	No	No	No
openness	Yes	No	No	No

As nouns, openness is a hyponym of willingness; that is, openness is a word with a more specific, narrower meaning than willingness:

willingness: cheerful compliance
openness: willingness or readiness to receive (especially impressions or ideas)

Other hyponyms of willingness include eagerness, forwardness, readiness, zeal, receptiveness, receptivity, wholeheartedness.

willingness (noun)	openness (noun)
cheerful compliance	characterized by an attitude of ready accessibility (especially about one's actions or purposes); without concealment; not secretive
	willingness or readiness to receive (especially impressions or ideas)
	without obstructions to passage or view